Bidirectional causal relationship between 91 blood cells and endometriosis at different sites: A Mendelian randomization study

To explore the genetic associations between 91 types of blood cells (BCs) and endometriosis (EMs), providing references for the treatment of EMs. Forward Mendelian randomization (MR) analysis was conducted with BC-related single nucleotide polymorphisms (SNPs) as instrumental variables and EMs as the outcome. Conversely, reverse MR analysis was performed using EMs-related SNPs as instrumental variables and BCs as the outcome. These analyses were carried out using the TwoSampleMR package in R. The forward MR analysis revealed significant genetic correlations between EMs and 4 BCs overall (P < .05). Specifically, significant correlations were observed between EMs and 2 BCs in the fallopian tube, 6 BCs in the intestine, 4 BCs in the ovary, 4 BCs in the pelvic peritoneum, 2 BCs in the rectovaginal septum and vagina, 5 BCs in skin scar, 7 BCs in the uterus, 9 BCs in other unclassified locations EMs (P < .05). The reverse MR analysis demonstrated significant genetic correlations between EMs and 3 types of BCs (P < .05), while no statistically significant correlations were found for the others (P > .05). EMsOI showed a significant genetic correlation with 1 BC (P < .05). No one were observed for BCs in EMsOFT. Eight BCs in EMsOO, 5 BCs in EMsOPP, 3 BCs in EMsORSV, 3 BCs in EMsOSS, 3 BCs in EMsOU and 5 BCs in U-EMs showed genetic correlations (P < .05). These associations between EMs and BCs exhibit a new perspective on the bidirectional causal relationships between BCs and EMs.